at91: at91-ohci: support overcurrent notification

Several USB power switches (AIC1526 or MIC2026) have a digital output
that is used to notify that an overcurrent situation is taking
place. This digital outputs are typically connected to GPIO inputs of
the processor and can be used to be notified of those overcurrent
situations.

Therefore, we add a new overcurrent_pin[] array in the at91_usbh_data
structure so that boards can tell the AT91 OHCI driver which pins are
used for the overcurrent notification, and an overcurrent_supported
boolean to tell the driver whether overcurrent is supported or not.

The code has been largely borrowed from ohci-da8xx.c and
ohci-s3c2410.c.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/include/mach/board.h

@@ -99,6 +99,10 @@ struct at91_usbh_data {
 	u8		ports;		/* number of ports on root hub */
 	u8		vbus_pin[2];	/* port power-control pin */
 	u8              vbus_pin_inverted;
+	u8              overcurrent_supported;
+	u8              overcurrent_pin[2];
+	u8              overcurrent_status[2];
+	u8              overcurrent_changed[2];
 };
 extern void __init at91_add_device_usbh(struct at91_usbh_data *data);
 extern void __init at91_add_device_usbh_ohci(struct at91_usbh_data *data);

drivers/usb/host/ohci-at91.c

@@ -218,6 +218,156 @@ ohci_at91_start (struct usb_hcd *hcd)
 	return 0;
 }
 
+static void ohci_at91_usb_set_power(struct at91_usbh_data *pdata, int port, int enable)
+{
+	if (port < 0 || port >= 2)
+		return;
+
+	gpio_set_value(pdata->vbus_pin[port], !pdata->vbus_pin_inverted ^ enable);
+}
+
+static int ohci_at91_usb_get_power(struct at91_usbh_data *pdata, int port)
+{
+	if (port < 0 || port >= 2)
+		return -EINVAL;
+
+	return gpio_get_value(pdata->vbus_pin[port]) ^ !pdata->vbus_pin_inverted;
+}
+
+/*
+ * Update the status data from the hub with the over-current indicator change.
+ */
+static int ohci_at91_hub_status_data(struct usb_hcd *hcd, char *buf)
+{
+	struct at91_usbh_data *pdata = hcd->self.controller->platform_data;
+	int length = ohci_hub_status_data(hcd, buf);
+	int port;
+
+	for (port = 0; port < ARRAY_SIZE(pdata->overcurrent_pin); port++) {
+		if (pdata->overcurrent_changed[port]) {
+			if (! length)
+				length = 1;
+			buf[0] |= 1 << (port + 1);
+		}
+	}
+
+	return length;
+}
+
+/*
+ * Look at the control requests to the root hub and see if we need to override.
+ */
+static int ohci_at91_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
+				 u16 wIndex, char *buf, u16 wLength)
+{
+	struct at91_usbh_data *pdata = hcd->self.controller->platform_data;
+	struct usb_hub_descriptor *desc;
+	int ret = -EINVAL;
+	u32 *data = (u32 *)buf;
+
+	dev_dbg(hcd->self.controller,
+		"ohci_at91_hub_control(%p,0x%04x,0x%04x,0x%04x,%p,%04x)\n",
+		hcd, typeReq, wValue, wIndex, buf, wLength);
+
+	switch (typeReq) {
+	case SetPortFeature:
+		if (wValue == USB_PORT_FEAT_POWER) {
+			dev_dbg(hcd->self.controller, "SetPortFeat: POWER\n");
+			ohci_at91_usb_set_power(pdata, wIndex - 1, 1);
+			goto out;
+		}
+		break;
+
+	case ClearPortFeature:
+		switch (wValue) {
+		case USB_PORT_FEAT_C_OVER_CURRENT:
+			dev_dbg(hcd->self.controller,
+				"ClearPortFeature: C_OVER_CURRENT\n");
+
+			if (wIndex == 1 || wIndex == 2) {
+				pdata->overcurrent_changed[wIndex-1] = 0;
+				pdata->overcurrent_status[wIndex-1] = 0;
+			}
+
+			goto out;
+
+		case USB_PORT_FEAT_OVER_CURRENT:
+			dev_dbg(hcd->self.controller,
+				"ClearPortFeature: OVER_CURRENT\n");
+
+			if (wIndex == 1 || wIndex == 2) {
+				pdata->overcurrent_status[wIndex-1] = 0;
+			}
+
+			goto out;
+
+		case USB_PORT_FEAT_POWER:
+			dev_dbg(hcd->self.controller,
+				"ClearPortFeature: POWER\n");
+
+			if (wIndex == 1 || wIndex == 2) {
+				ohci_at91_usb_set_power(pdata, wIndex - 1, 0);
+				return 0;
+			}
+		}
+		break;
+	}
+
+	ret = ohci_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
+	if (ret)
+		goto out;
+
+	switch (typeReq) {
+	case GetHubDescriptor:
+
+		/* update the hub's descriptor */
+
+		desc = (struct usb_hub_descriptor *)buf;
+
+		dev_dbg(hcd->self.controller, "wHubCharacteristics 0x%04x\n",
+			desc->wHubCharacteristics);
+
+		/* remove the old configurations for power-switching, and
+		 * over-current protection, and insert our new configuration
+		 */
+
+		desc->wHubCharacteristics &= ~cpu_to_le16(HUB_CHAR_LPSM);
+		desc->wHubCharacteristics |= cpu_to_le16(0x0001);
+
+		if (pdata->overcurrent_supported) {
+			desc->wHubCharacteristics &= ~cpu_to_le16(HUB_CHAR_OCPM);
+			desc->wHubCharacteristics |=  cpu_to_le16(0x0008|0x0001);
+		}
+
+		dev_dbg(hcd->self.controller, "wHubCharacteristics after 0x%04x\n",
+			desc->wHubCharacteristics);
+
+		return ret;
+
+	case GetPortStatus:
+		/* check port status */
+
+		dev_dbg(hcd->self.controller, "GetPortStatus(%d)\n", wIndex);
+
+		if (wIndex == 1 || wIndex == 2) {
+			if (! ohci_at91_usb_get_power(pdata, wIndex-1)) {
+				*data &= ~cpu_to_le32(RH_PS_PPS);
+			}
+
+			if (pdata->overcurrent_changed[wIndex-1]) {
+				*data |= cpu_to_le32(RH_PS_OCIC);
+			}
+
+			if (pdata->overcurrent_status[wIndex-1]) {
+				*data |= cpu_to_le32(RH_PS_POCI);
+			}
+		}
+	}
+
+ out:
+	return ret;
+}
+
 /*-------------------------------------------------------------------------*/
 
 static const struct hc_driver ohci_at91_hc_driver = {
@@ -253,8 +403,8 @@ static const struct hc_driver ohci_at91_hc_driver = {
 	/*
 	 * root hub support
 	 */
-	.hub_status_data =	ohci_hub_status_data,
-	.hub_control =		ohci_hub_control,
+	.hub_status_data =	ohci_at91_hub_status_data,
+	.hub_control =		ohci_at91_hub_control,
 #ifdef CONFIG_PM
 	.bus_suspend =		ohci_bus_suspend,
 	.bus_resume =		ohci_bus_resume,
@@ -264,22 +414,71 @@ static const struct hc_driver ohci_at91_hc_driver = {
 
 /*-------------------------------------------------------------------------*/
 
+static irqreturn_t ohci_hcd_at91_overcurrent_irq(int irq, void *data)
+{
+	struct platform_device *pdev = data;
+	struct at91_usbh_data *pdata = pdev->dev.platform_data;
+	int val, gpio, port;
+
+	/* From the GPIO notifying the over-current situation, find
+	 * out the corresponding port */
+	gpio = irq_to_gpio(irq);
+	for (port = 0; port < ARRAY_SIZE(pdata->overcurrent_pin); port++) {
+		if (pdata->overcurrent_pin[port] == gpio)
+			break;
+	}
+
+	if (port == ARRAY_SIZE(pdata->overcurrent_pin)) {
+		dev_err(& pdev->dev, "overcurrent interrupt from unknown GPIO\n");
+		return IRQ_HANDLED;
+	}
+
+	val = gpio_get_value(gpio);
+
+	/* When notified of an over-current situation, disable power
+	   on the corresponding port, and mark this port in
+	   over-current. */
+	if (! val) {
+		ohci_at91_usb_set_power(pdata, port, 0);
+		pdata->overcurrent_status[port]  = 1;
+		pdata->overcurrent_changed[port] = 1;
+	}
+
+	dev_dbg(& pdev->dev, "overcurrent situation %s\n",
+		val ? "exited" : "notified");
+
+	return IRQ_HANDLED;
+}
+
+/*-------------------------------------------------------------------------*/
+
 static int ohci_hcd_at91_drv_probe(struct platform_device *pdev)
 {
 	struct at91_usbh_data	*pdata = pdev->dev.platform_data;
 	int			i;
 
 	if (pdata) {
-		/* REVISIT make the driver support per-port power switching,
-		 * and also overcurrent detection.  Here we assume the ports
-		 * are always powered while this driver is active, and use
-		 * active-low power switches.
-		 */
 		for (i = 0; i < ARRAY_SIZE(pdata->vbus_pin); i++) {
 			if (pdata->vbus_pin[i] <= 0)
 				continue;
 			gpio_request(pdata->vbus_pin[i], "ohci_vbus");
-			gpio_direction_output(pdata->vbus_pin[i], pdata->vbus_pin_inverted);
+			ohci_at91_usb_set_power(pdata, i, 1);
+		}
+
+		for (i = 0; i < ARRAY_SIZE(pdata->overcurrent_pin); i++) {
+			int ret;
+
+			if (pdata->overcurrent_pin[i] <= 0)
+				continue;
+			gpio_request(pdata->overcurrent_pin[i], "ohci_overcurrent");
+
+			ret = request_irq(gpio_to_irq(pdata->overcurrent_pin[i]),
+					  ohci_hcd_at91_overcurrent_irq,
+					  IRQF_SHARED, "ohci_overcurrent", pdev);
+			if (ret) {
+				gpio_free(pdata->overcurrent_pin[i]);
+				dev_warn(& pdev->dev, "cannot get GPIO IRQ for overcurrent\n");
+			}
 		}
 	}
 
@@ -296,9 +495,16 @@ static int ohci_hcd_at91_drv_remove(struct platform_device *pdev)
 		for (i = 0; i < ARRAY_SIZE(pdata->vbus_pin); i++) {
 			if (pdata->vbus_pin[i] <= 0)
 				continue;
-			gpio_direction_output(pdata->vbus_pin[i], !pdata->vbus_pin_inverted);
+			ohci_at91_usb_set_power(pdata, i, 0);
 			gpio_free(pdata->vbus_pin[i]);
 		}
+
+		for (i = 0; i < ARRAY_SIZE(pdata->overcurrent_pin); i++) {
+			if (pdata->overcurrent_pin[i] <= 0)
+				continue;
+			free_irq(gpio_to_irq(pdata->overcurrent_pin[i]), pdev);
+			gpio_free(pdata->overcurrent_pin[i]);
+		}
 	}
 
 	device_init_wakeup(&pdev->dev, 0);